1. Field of the Invention
The present invention relates, in general, to a device for measuring pressure tension or pull force on a rope or cable.
2. Information Disclosure Statement
A preliminary patentability search conducted in class 73 produced the following patents which appear to be relevant to the present invention:
Warren et al., U.S. Pat. No. 28,925, issued Jun. 26, 1860. The Warren et al. patent discloses a dynamometer for measuring the power transmitted by shafting to machinery. The Warren et al. dynamometer includes a first pulley fixedly attached to a shalt, a second pulley movably attached to a shaft, and one or more arms and spiral springs combining the two pulleys with a scale attached to one of the pulleys for indicating the relative power transmitted between the pulleys.
Murdock, U.S. Pat. No. 380,294, issued Mar. 27, 1888. The Murdock patent discloses a dynamometer for determining the force required to drive machines in an industrial establishment. The Murdock dynamometer includes a pulley loosely mounted on a shaft, a coil spring joining the pulley to the shaft so that when the shaft is rotated and resistance is applied to the pulley, the spring will be deflected and amount proportional to the resistance. A pointer is carried by the shaft for indicating how much the spring deflects.
Moore, U.S. Pat. No. 930,605, issued Aug. 10, 1909. The Moore patent discloses a transmission dynamometer including a rotary shaft, a first rotary member secured to the shaft, a second rotary member connected to the first rotary member by springs so that the force applied to or by the shaft is proportional to the amount that the springs deflect.
Wunsch et al. U.S. Pat. No. 2,025,928, issued Dec. 31, 1935. The Wunsch et al. patent discloses a hoisting mechanism including means for indicating the pull on the hoist rope or cable. The Wunsch et al. mechanism includes a support frame, a pivot support for one part of the frame and a resilient support for another part of the frame, a driving shaft rotatably supported by the frame, a winding drum carried on the shaft, a pulling cable secured to the drum, a lever associated with the frame and actuated by movement of the frame caused by a tangentially component of the torque of the driving shaft, and means connected to the lever for indicating the pull on the cable.
Chinn, U.S. Pat. No. 2,491,251, issued Dec. 13, 1949. The Chinn patent discloses a torsion dynamometer including a split annular spring, means or applying torque to the spring to effect a deflection of the adjacent ends of the spring relative to each other, an amount proportion to the torque, and valve means controlled by the deflection of the ends of the spring for varying the flow of a fluid according to the relative deflection of the ends of the spring.
Webber, U.S. Pat. No. 2,656,719, issued Oct. 27, 1953. The Webber patent discloses a traveling line load indicator for indicating the lifting load applied to tool hoisting lines or cables in deep well or mining operations. The Webber indicator includes a fulcrum, lever means pivotally mounted on the fulcrum, bearings provided on the lever means, a line wheel rotatably mounted in the bearings to receive a turn of a line thereabout whereby the line is adapted to depend from the wheel into a well and be supported on the wheel while travelling into or from the well, a load measuring device connected to the lever means and adapted to absorb the load imposed on the wheel by the line which tends to rotate the lever means about the fulcrum, the axis of the line wheel being slightly inclined relative to horizontal, and a guide wheel for guiding the line into substantially tangential contact with a lower portion of the periphery of the line wheel whereby the line may be passed substantially once around the line wheel and extend vertically therefrom into the well, the portion of the line between the guide wheel and the line wheel being spaced, by virtue of the inclination of the axis, from the portion of the line which depends from the line wheel.
Lodge, U.S. Pat. No. 2,695,519, issued Nov. 30, 1954. The Lodge patent discloses a tension indicator for measuring and regulating the tension of yarn ends as they are drawn from section beams or spools through a slasher onto a loom beam, etc. The Lodge tension indicator includes a pair of fixed rollers over which strands of yarn or the like are adapted to pass, a floating arm adapted to lie upon the strands and between the rollers, a transformer having a movable armature and a primary and secondary coil, means to transmit movement of the floating arm to move the armature, an electrical circuit connected to the transformer secondary coil and an electric meter connected in the circuit and thereby responsive to the positioning of the movable armature to indicate the tension of the strands.
Grimes, U.S. Pat. No. 2,826,065, issued Mar. 11, 1958. The Grimes patent discloses an apparatus for determining resistance of earth anchors embedded in soils against displacement under applied loads. The Grimes apparatus includes a rig frame, a boom attached to the rig frame, a cable attached to the anchor at substantially right angles thereto and at the center thereof, a source of power for tensioning the cable, a pulley sheave carried by the boom and receiving the cable, compression spring mountings for applying a predetermined force to the sheave opposite to the force applied to the sheave by the cable, the sheave being yieldable against the spring mountings when the force applied to the sheave by the cable exceeds the predetermined force applied by the spring mountings, and means adjacent to the sheave for indicating the amount of force on the cable which causes the sheave to move against the force of the springs, thereby measuring force imparted to the anchor by the source of power.
Habern et al., U.S. Pat. No. 3,330,154, issued Jul. 11, 1967. The Habern et al. patent discloses an apparatus for measuring the resultant load on a stationary shaft. The Habern apparatus includes a cylindrical shaft for being inserted through a rotatable member along the axis thereof and defining a cavity in an end thereof which is subject to incremental changes in dimensions in response to pressure variations exerted on the shaft by the rotatable member, the cavity being circular in cross-section and tapered inward from the end of the shaft concentric with the axis thereof, and a transducer disposed with the cavity having a pair of opposing curved ends abutting the walls of the cavity with the ends being tapered to match the taper of the cavity and being strained in response to the incremental changes in dimensions of the cavity, the transducer having strain gage means mounted thereon which is strained in proportion to the strain applied to the transducer.
Gibson et al., U.S. Pat. No. 4,372,535, issued Feb. 8, 1983. The Gibson et al. patent discloses a capstan winch for pulling cable through conduit, including means for measuring the torque applied to the capstan and a take-up reel. The torque measuring means includes an inner drum connected by a tension spring to a concentric outer drum. A patterned disc on the inner drum is visible through a window in the outer drum. The pattern indicates the relative position of the inner and outer drums, which is correlated to the applied torque.
Marshek et al., U.S. Pat. No. 4,841,783, issued Jun. 27, 1989. The Marshek et al. patent discloses a machine for measuring normal and tangential belt forces versus angular position for a flat belt drive. The Marshek et al. machine includes a normal force transducer driving pulley with two curved beams for measuring normal force, a tangential force transducer driven pulley with a cantilever beam for measuring tangential force, a torque disk connected to the driven pulley, first and second transverse sliding plates on which respectively the driving and driven pulleys each are separately mounted, input power supply means connected to the driving pulley to supply input power to the driving pulley, and means for applying belt initial tension through the second transverse sliding plate by applying tension to a first cord operatively connected to the second transverse sliding plate and wound at least partially on a roller.
Bridges, U.S. Pat. No. 5,193,401, issued Mar. 16, 1993. The Bridges patent discloses an apparatus for direct measurement of torque in an articulated joint including a driver assembly and a driven assembly with the driver assembly and driven assembly mounted on a common axis for enabling angular displacement of the driven assembly relative to the driver assembly about the common axis. An interlock is provided and is responsive to a remote actuator for rotating the driven assembly relative to the driver assembly. At least one force sensor is disposed in a position for transmitting rotational force from the interlock to the driven assembly and for measuring the rotational force in order to provide a torque measurement.
Nothing in the known prior art discloses or suggests the present invention. More specifically, nothing in the known prior art discloses or suggests a pull measuring device including an elongated cable having a first end, a second end, and a midportion located between the first and second ends thereof; a support member; a pulley rotatably mounted on the support member, the pulley having an outer edge about which the midportion of the cable is wrapped; the pulley having a transverse slot through at least one edge thereof; the transverse slot having at least one opened end with opposing lips so that when the midportion of the cable is wrapped about the outer edge of the pulley and a pulling force is applied to one end of the cable, the opposing lips of the opened end of the slot will be urged toward one another an amount proportion to the pulling force applied to the cable; and measuring means for measuring the movement of the opposing lips of the opened end of the slot toward one another.